#ifndef CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED

#define CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED

#include <cppunit/Portability.h>

#include <math.h>

#if defined(__sun) && !defined(CPPUNIT_HAVE_ISFINITE) && defined(CPPUNIT_HAVE_FINITE)

#include <ieeefp.h>

  // <math.h> is still needed for usage of fabs in TestAssert.cpp

#endif

CPPUNIT_NS_BEGIN

/// \brief Tests if a floating-point is a NaN.

// According to IEEE-754 floating point standard, 

// (see e.g. page 8 of

// http://www.cs.berkeley.edu/~wkahan/ieee754status/ieee754.ps) 

// all comparisons with NaN are false except "x != x", which is true.

//

// At least Microsoft Visual Studio 6 is known not to implement this test correctly.

// It emits the following code to test equality:

//  fcomp       qword ptr [nan]

//  fnstsw      ax                        // copie fp (floating-point) status register to ax

//  test        ah,40h                    // test bit 14 of ax (0x4000) => C3 of fp status register

// According to the following documentation on the x86 floating point status register,

// the C2 bit should be tested to test for NaN value. 

// http://webster.cs.ucr.edu/AoA/Windows/HTML/RealArithmetic.html#1000117

// In Microsoft Visual Studio 2003 & 2005, the test is implemented with:

//  test        ah,44h         // Visual Studio 2005 test both C2 & C3...

//

// To work around this, a NaN is assumed to be detected if no strict ordering is found.

inline bool floatingPointIsUnordered( double x )

{

   // x != x will detect a NaN on conformant platform

   // (2.0 < x  &&  x < 1.0) will detect a NaN on non conformant platform:

   // => no ordering can be found for x.

   return  (x != x) ||  (2.0 < x  &&  x < 1.0);

}

/// \brief Tests if a floating-point is finite.

/// @return \c true if x is neither a NaN, nor +inf, nor -inf, \c false otherwise.

inline int floatingPointIsFinite( double x )

{

#if defined(CPPUNIT_HAVE_ISFINITE)

   return isfinite( x );

#elif defined(CPPUNIT_HAVE_FINITE)

   return finite( x );

#elif defined(CPPUNIT_HAVE__FINITE)

   return _finite(x);

#else

   double testInf = x * 0.0;  // Produce 0.0 if x is finite, a NaN otherwise.

   return testInf == 0.0  &&  !floatingPointIsUnordered(testInf);

#endif

}

CPPUNIT_NS_END

#endif // CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED